A defiant Saddam Hussein refused to wear a hood over his head before the noose was wrapped around his neck and a trap door dropped beneath his feet, eyewitnesses to Saturday's hanging said.

The ousted leader mounted the gallows inside a former torture centre in Kadhimiyah in northern Baghdad and was hanged just before 6:00 am (0300 GMT), said National Security Adviser Mowaffaq al-Rubaie, who was among those present.

Iraqi state television showed a brief film of Saddam being placed in a noose by masked hangmen, cutting away just before his execution.

The 69-year-old leader appeared calm, chatting to his burly, leather-jacketed executioners as they wrapped his neck first in black cloth then a thick hemp rope and steered him forward on a metal platform.

The gallows was constructed in red-painted metal and was fixed inside a dim room with blue-grey walls. The guards wore black balaclava-style hoods.

Saddam was manoeuvred forward firmly but not aggressively by the guards, the grey-bearded prisoner looking thin inside a smart, dark overcoat over a pressed white shirt but no tie.

Members of a small group of dignitaries who formally witnessed the execution said Saddam showed no sign of remorse in the final moments before being hanged for crimes against humanity.

Rubaie said in a series of televised interviews that the former strongman did not attempt to resist his executioners.

"He did not try to resist... He was holding a Koran in his hands that he wanted to have sent to someone, so the name of the person was taken down," Rubaie said.

"Saddam mounted the gallows calmly, without saying a word. He was resolute and courageous ... At one point, he turned his head toward me as if to say 'don't be afraid'," Rubaie said. "It was a very strange feeling."

Once on the gallows, Saddam "refused to allow a guard to place a hood over his head. They stared at each other briefly" before the guard stepped away, granting Saddam's wish to leave his face uncovered, said Rubaie.

Saddam had an opportunity to speak his final words.

"He said 'I hope you will be united, and I warn you not to trust the Iranian coalition, because they are dangerous'," Judge Moneer Haddad, who witnessed Saddam's execution for crimes against humanity, told AFP.

"He said he was not afraid of anyone," Haddad said.

The taunt was a last stab at Maliki's Shia-led ruling coalition, which many Iraqi Sunnis accuse of being a front for Iranian influence.

"He was asked for his last words," said Shia lawmaker Sami al-Askari. "The rope was then wrapped around his neck, his hands were tied, and he was immediately executed."

Rubaie said death came rapidly.

"It went like a blink of an eye. He died very, very quickly. It couldn't have been quicker."

State television prepared the ground for Saddam's execution by showing gruesome footage of his soldiers mutilating and beating prisoners, throwing a detainee from a roof and filling mass graves.

A 36-year-old engineer told AFP that he was given the opportunity view the body because members of his family had fallen victim to Saddam's brutal regime.

"I saw him after the execution," said Jawad Abdul-Aziz Al-Zubaidi. "He was inside an ambulance. His neck was broken. He was wearing black coat and a white shirt without a tie. His beard was long and his hair was long."

Zubaidi, who testified in the case that saw Saddam condemned for his role in the killings of 148 Shia villagers from Dujail in 1982, said he had viewed the body along with some Iraqi officials.

It was a moment of "happiness for all Iraqis", he said, adding that Saddam, had "executed three of my brothers and my father".

Saddam's American jailers had handed him over to Iraqi officials and there were no US personnel in the building as the trapdoor dropped and Saddam's life was ended.

"This was a 100 percent Iraqi process," said Rubaie. "There were only Iraqis present, no foreigners. The Americans were not present at the execution."